This invention relates to a digital switching matrix of a telephone system, and more particularly, to redundancy in a digital switch matrix. Essentially all electronic systems, computer systems, telephone systems, etc., developed by man have from time to time experienced a failure or malfunction resulting in system, or partial system downtime. In order to maintain system operability, many techniques have been devised to increase the reliability and decrease system downtime. One particular scheme utilized by systems designers is the duplication of systems or subsystems, but oftentimes this approach can be economically not feasible.
Therefore, in a telephone system which includes a plurality of digital switches, there is included in the present invention a single standby digital switch, and associated enabling logic, which can be operationally substituted for any one of the plurality of digital switches thereby achieving a redundancy for all of the plurality of digital switches by a single additional switch (i.e., the standby switch).